Chapter 26. Capacitance and Dielectrics


 Jacob Reed
 2 years ago
 Views:
Transcription
1 Chapter 26 Capacitance and Dielectrics
2 Capacitors Capacitors are devices that store electric charge Examples where capacitors are used: radio receivers filters in power supplies energystoring devices in electronic flashes
3 Definition of Capacitance The capacitance, C, of a capacitor is defined as the ratio of the magnitude of the charge on either conductor to the potential difference between the conductors C Capacitance is a positive quantity. It is a measure of the ability to store charge The SI unit of capacitance is the farad (F) large, e.g. microfarads (µf) or picofarads (pf) Q V
4 Makeup of a Capacitor A capacitor consists of two conductors These are called plates When the plates are charged, they have equal and opposite charges A potential difference exists between the plates due to this charge
5 Quick Quiz 26.1 A capacitor stores charge Q at a potential difference ΔV. If the voltage applied by a battery to the capacitor is doubled to 2ΔV: (a) the capacitance falls to half its initial value and the charge remains the same (b) the capacitance and the charge both fall to half their initial values (c) the capacitance and the charge both double (d) the capacitance remains the same and the charge doubles
6 Quick Quiz 26.1 Answer: (d). The capacitance is a property of the physical system and does not vary with applied voltage. According to C=Q/ V, if the voltage is doubled, the charge is doubled.
7 Demo Ea9: Parallel plate capacitor and plate separation Voltage proportional to distance between plates V=Ed Voltage decreases on inserting dielectric between plates V = Q/κC 0
8 Parallel Plate Capacitor Each plate is connected to a terminal of the battery Suppose initially uncharged Battery then establishes an electric field in the connecting wires
9 Parallel Plate Capacitor Consider, first, the negative terminal: Field applies a force on electrons in the wire Force causes the electrons to move onto the negative plate Continues until equilibrium is achieved i.e. the plate, wire and terminal are all at the same potential There is now no field present in the wire Hence the movement of electrons ceases The plate is now negatively charged
10 Parallel Plate Capacitor Now consider the positive terminal A similar process occurs at the other plate, with electrons moving away from the plate and leaving it positively charged In its final configuration, the potential difference across the capacitor plates is the same as that between the terminals of the battery
11 Capacitance Parallel Plates Charge density σ = Q/A Electric field E = / 0 (for conductor) Uniform between plates, zero elsewhere C Q V Q Ed Q Q 0 A d 0 A i.e. proportional to the area of plates and inversely proportional to the distance between them d
12 Parallel Plate Assumptions Assumption that electric field is uniform is valid in the central region, but not at the ends of the plates If separation between plates is small compared with their length, effect of nonuniform field can be ignored
13 Quick Quiz 26.2 Many computer keyboard buttons are constructed of capacitors, as shown in the figure below. When a key is pushed down, the soft insulator between the movable plate and the fixed plate is compressed. When the key is pressed, the capacitance (a) increases (b) decreases (c) changes in a way that we cannot determine because the complicated electric circuit connected to the keyboard button may cause a change in ΔV.
14 Quick Quiz 26.2 Answer: (a). When the key is pressed, the plate separation is decreased and the capacitance increases (since C= 0 A/d). Capacitance depends only on how a capacitor is constructed and not on the external circuit.
15 Capacitance of Isolated Sphere Assume a spherical charged conductor Assume V = 0 at infinity. Then C Q V Q k e Q / R R k e 4 0 R independent of charge and potential difference
16 Spherical Capacitor (ex 26.3) V b a E r dr k e Q b dr k Q 1 r 2 e r a a b k e Q 1 b 1 a C Q V 1 1 k e 1 a b
17 Cylindrical Capacitor (ex. 26.2) Q= l E = 2k e / r From Gauss s Law (exercise ) V C Q V b a E r dr b dr 2 k e 2 k e ln b r a l 2 k e ln b a a
18 Geometry of Some Capacitors
19 Circuit Symbols A circuit diagram is a simplified representation of an actual circuit Circuit symbols are used to represent the various elements Lines are used to represent wires The battery s positive terminal is indicated by the longer line
20 ECM05ANA: Charging & Discharging a Capacitor
21 Capacitors in Parallel When capacitors are first connected in the circuit, electrons are transferred from the left plates through the battery to the right plate, leaving the left plate positively charged and the right plate negatively charged
22 Capacitors in Parallel, 2 The flow of charges ceases when the voltage across the capacitors equals that of the battery Maximum charge Total charge is sum of the charges Q total = Q 1 + Q 2 Potential difference across the capacitors is the same, equal to voltage of battery (V=V 1 =V 2 ) Hence Q total /V = Q 1 /V 1 + Q 2 /V 2, so C eq = C 1 + C 2
23 Capacitors in Parallel, 3 Capacitors can be replaced with one capacitor with a capacitance of C eq The equivalent capacitor must have exactly the same external effect on the circuit as the original capacitors
24 Capacitors in Series When a battery is connected to the circuit, electrons are transferred from the left plate of C 1 to the right plate of C 2 through the battery
25 Capacitors in Series, 2 As negative charge accumulates on right plate of C 2, an equivalent amount of negative charge is removed from left plate of C 2, leaving it with excess positive charge All the right plates gain charges of Q, all left plates have charges of +Q
26 Capacitors in Series, 3 The potential differences add up to the battery voltage Q Q 1 Q 2 V V 1 V 2 V Q V 1 Q 1 V 2 Q 2 1 C 1 C 1 1 C 2
27 Capacitors in Combination When two or more capacitors are connected in parallel, the potential differences across them are the same Charge on each capacitor proportional to its capacitance Capacitors add directly to give the equivalent capacitance When two or more capacitors are connected in series, they carry the same charge, but the potential differences across them are not the same Capacitances add as reciprocals Equivalent capacitance always less than smallest individual capacitor
28 Equivalent Capacitance (exercise) The 1.0µF and 3.0µF capacitors are in parallel as are the 6.0µF and 2.0µF capacitors These parallel combinations are in series with the capacitors next to them The series combinations are in parallel and the final equivalent capacitance can be found
29 Quick Quiz 26.3 Two capacitors are identical. They can be connected in series or in parallel. If you want the smallest equivalent capacitance for the combination, you should connect them in (a) series (b) parallel (c) Either combination has the same capacitance.
30 Quick Quiz 26.3 Answer: (a). When connecting capacitors in series, the inverses of the capacitances add (1/C = 1/C 1 + 1/C 2 ), resulting in a smaller overall equivalent capacitance.
31 Quick Quiz 26.4 Consider two identical capacitors. Each capacitor is charged to a voltage of 10 V. If you want the largest combined potential difference across the combination, you should connect them in (a) series (b) parallel (c) Either combination has the same potential difference.
32 Quick Quiz 26.4 Answer: (a). When capacitors are connected in series, the voltages add, for a total of 20 V in this case. If they are combined in parallel, the voltage across the combination is still 10 V.
33 Exercise Connect plates of capacitor to battery. What happens to the charge when the connecting wires to the battery are removed? Nothing! Charge remains on the plates. What happens if the wires are now connected to one another? Charges move along wires and plates until the entire conductor is at a single potential and the capacitor is discharged.
34 Demo Eb14 Energy Storage in Capacitor Charge up capacitor using DC power supply. Disconnect and attach leads to electric motor. Rotation of motor enables work to be done.
35 ECA05AN2: Energy storage in a capacitor
36 Energy in a Capacitor Overview Before switch is closed, energy is stored as chemical energy in battery When switch is closed, energy is then transformed from chemical to electric potential energy
37 Energy in a Capacitor Overview, cont Electric potential energy related to separation of positive and negative charges on plates Thus, a capacitor is a device that stores energy as well as charge
38 Energy Stored in a Capacitor Assume capacitor is being charged and, at some point, has a charge q on it and a potential difference V The work then needed to transfer a charge dq from one plate to the other is d W V d q q d q C The total work required is W Q q d q Q C 0 C 2 2
39 Energy, cont The work done in charging the capacitor appears as electric potential energy U: (remember C = Q/ V) Applies in any geometry 2 U Q 1 Q V 1 C ( V ) 2C 2 2 Energy stored increases as charge increases and as potential difference increases In practice, there is a maximum voltage before discharge occurs between the plates 2
40 Energy, final Energy is stored in the electric field For parallelplate capacitor, the energy can be expressed in terms of the field: U = ½ C V 2 =½ (ε o A/d)(Ed) 2 = ½ (ε o Ad)E 2 Can also be expressed as the energy density (energy per unit volume [Ad]) u E = U/[Ad] = ½ ε o E 2
41 Quick Quiz 26.5 You have three capacitors and a battery. In which of the following combinations of the three capacitors will the maximum possible energy be stored when the combination is attached to the battery? (a) series (b) parallel (c) Both combinations will store the same amount of energy.
42 Quick Quiz 26.5 Answer: (b). For a given voltage, the energy stored in a capacitor is proportional to C: U = C(ΔV) 2 /2. Thus, you want to maximize the equivalent capacitance and the potential difference cross it. You do this by connecting the three capacitors in parallel, so that the capacitances add, and each capacitor has the same potential difference, ΔV, across it.
43 Quick Quiz 26.6 You charge a parallelplate capacitor, remove it from the battery, and prevent the wires connected to the plates from touching each other. When you pull the plates apart to a larger separation, do the following quantities increase, decrease, or stay the same? (a) C; (b) Q; (c) E between the plates; (d) ΔV ; (e) energy stored in the capacitor.
44 Quick Quiz 26.6 Answers: (a) C decreases (C= 0 A/d). (b) Q stays the same because there is no place for the charge to flow. (c) E remains constant (E= /2 0 ). (d) ΔV increases because ΔV = Q/C, Q is constant (part b), and C decreases (part a). (e) The energy stored in the capacitor is proportional to both Q and ΔV 2 and thus increases. The additional energy comes from the work you do in pulling the two plates apart.
45 Quick Quiz 26.7 Repeat Quick Quiz 26.6, but this time answer the questions for the situation in which the battery remains connected to the capacitor while you pull the plates apart. Do this in your own time.
46 Quick Quiz 26.7 Answers: (a) C decreases (C= 0 A/d). (b) Q decreases. The battery supplies a constant potential difference ΔV; thus, charge must flow out of the capacitor if C = Q /ΔV is to decrease. (c) E decreases because the charge density on the plates decreases. (d) ΔV remains constant because of the presence of the battery. (e) The energy stored in the capacitor decreases (U = C(ΔV) 2 /2).
47 Some Uses of Capacitors Defibrillators When fibrillation occurs, the heart produces a rapid, irregular pattern of beats A fast discharge of electrical energy through the heart can return the organ to its normal beat pattern In general, capacitors act as energy reservoirs that can be slowly charged and then discharged quickly to provide large amounts of energy in a short pulse
48 Demo Eb4 Energy storage in a capacitor Light bulb placed in series with a capacitor. Currents generated in charging and discharging the capacitor. Note that light bulb does not have constant resistance as the temperature changes.
49 Capacitors with Dielectrics A dielectric is a nonconducting material that, when placed between the plates of a capacitor, increases the capacitance Dielectrics include rubber, plastic, and waxed paper For a parallelplate capacitor C = κc o = κε o (A/d) The capacitance is multiplied by the factor κ when the dielectric completely fills the region between the plates
50 Dielectrics, cont In theory, d could be made very small to create a very large capacitance In practice, there is a limit to how small: d is limited by the electric discharge that could occur though the dielectric medium separating the plates For a given d, the maximum voltage that can be applied to a capacitor without causing a discharge depends on the dielectric strength of the material
51 Dielectrics, final Dielectrics provide the following advantages: Increase in capacitance Increase the maximum operating voltage Possible mechanical support between the plates Allows plates to be close together without touching This decreases d and increases C
52
53 Dielectrics An Atomic View (not examinable) The molecules that make up the dielectric are modeled as dipoles The molecules are randomly oriented in the absence of an electric field
54 Dielectrics Atomic View, 2 An external electric field is applied This produces a torque on the molecules The molecules partially align with the electric field
55 Induced Charge and Field The electric field due to the plates is directed to the right and it polarizes the dielectric The net effect on the dielectric is an induced surface charge that results in an induced electric field If the dielectric were replaced with a conductor, the net field between the plates would be zero
56 Quick Quiz 26.9 A fully charged parallelplate capacitor remains connected to a battery while you slide a dielectric between the plates. Do the following quantities increase, decrease, or stay the same? (a) C; (b) Q; (c) E between the plates; (d) ΔV.
57 Quick Quiz 26.9 Answers: (a) C increases (C= C 0 ). (b) Q increases. Because the battery maintains a constant ΔV, Q must increase if C increases (Q=C V). (c) E between the plates remains constant because ΔV = Ed and neither ΔV nor d changes. The electric field due to the charges on the plates increases because more charge has flowed onto the plates. However, the induced surface charges on the dielectric create a field that opposes the increase in the field caused by the greater number of charges on the plates. (d) The battery maintains a constant ΔV.
58 End of Chapter
59 Dielectrics Atomic View, 3 Degree of alignment of the molecules with the field depends on temperature and the magnitude of the field In general, the alignment increases with decreasing temperature the alignment increases with increasing field strength
60 Dielectrics Atomic View, 4 If the molecules of the dielectric are nonpolar molecules, the electric field produces some charge separation This produces an induced dipole moment The effect is then the same as if the molecules were polar
61 Dielectrics Atomic View, final An external field can polarize the dielectric whether the molecules are polar or nonpolar The charged edges of the dielectric act as a second pair of plates producing an induced electric field in the direction opposite the original electric field
62 Quick Quiz 26.8 If you have ever tried to hang a picture or a mirror, you know it can be difficult to locate a wooden stud in which to anchor your nail or screw. A carpenter s studfinder is basically a capacitor with its plates arranged side by side instead of facing one another, as shown in the figure below. When the device is moved over a stud, the capacitance will: (a) increase (b) decrease
63 Quick Quiz 26.8 Answer: (a). The dielectric constant of wood (and of all other insulating materials, for that matter) is greater than 1; therefore, the capacitance increases (C= C 0 ). This increase is sensed by the studfinder's special circuitry, which causes an indicator on the device to light up.
Fall 12 PHY 122 Homework Solutions #4
Fall 12 PHY 122 Homework Solutions #4 Chapter 23 Problem 45 Calculate the electric potential due to a tiny dipole whose dipole moment is 4.8 x 1030 C.m at a point 4.1 x 109 m away if this point is (a)
More informationChapter 25: Capacitance
Chapter 25: Capacitance Most of the fundamental ideas of science are essentially simple, and may, as a rule, be expressed in a language comprehensible to everyone. Albert Einstein 25.1 Introduction Whenever
More informationCapacitance and Dielectrics. Physics 231 Lecture 41
apacitance and Dielectrics Physics 3 Lecture 4 apacitors Device for storing electrical energy which can then be released in a controlled manner onsists of two conductors, carrying charges of q and q,
More information1 of 7 3/23/2010 2:45 PM
1 of 7 3/23/2010 2:45 PM Chapter 30 Homework Due: 8:00am on Tuesday, March 23, 2010 Note: To understand how points are awarded, read your instructor's Grading Policy. [Return to Standard Assignment View]
More informationLesson 6 Capacitors and Capacitance Lawrence B. Rees 2007. You may make a single copy of this document for personal use without written permission.
Lesson 6 apacitors and apacitance Lawrence B. Rees 7. You may make a single copy of this document for personal use without written permission. 6. Introduction In 745 Pieter van Musschenbroek, while trying
More informationCapacitance, Resistance, DC Circuits
This test covers capacitance, electrical current, resistance, emf, electrical power, Ohm s Law, Kirchhoff s Rules, and RC Circuits, with some problems requiring a knowledge of basic calculus. Part I. Multiple
More informationExam 1 Solutions. PHY2054 Fall 2014. Prof. Paul Avery Prof. Andrey Korytov Sep. 26, 2014
Exam 1 Solutions Prof. Paul Avery Prof. Andrey Korytov Sep. 26, 2014 1. Charges are arranged on an equilateral triangle of side 5 cm as shown in the diagram. Given that q 1 = 5 µc and q 2 = q 3 = 2 µc
More informationphysics 111N electric potential and capacitance
physics 111N electric potential and capacitance electric potential energy consider a uniform electric field (e.g. from parallel plates) note the analogy to gravitational force near the surface of the Earth
More informationPHYS2020: General Physics II Course Lecture Notes Section II
PHYS2020: General Physics II Course Lecture Notes Section II Dr. Donald G. Luttermoser East Tennessee State University Edition 4.0 Abstract These class notes are designed for use of the instructor and
More informationCHAPTER 26 ELECTROSTATIC ENERGY AND CAPACITORS
CHAPTER 6 ELECTROSTATIC ENERGY AND CAPACITORS. Three point charges, each of +q, are moved from infinity to the vertices of an equilateral triangle of side l. How much work is required? The sentence preceding
More informationCapacitors. February 5, 2014 Physics for Scientists & Engineers 2, Chapter 24 1
Capacitors February 5, 2014 Physics for Scientists & Engineers 2, Chapter 24 1 Review! The electric potential energy stored in a capacitor is given by! The field energy density stored in a parallel plate
More informationPreLab 7 Assignment: Capacitors and RC Circuits
Name: Lab Partners: Date: PreLab 7 Assignment: Capacitors and RC Circuits (Due at the beginning of lab) Directions: Read over the Lab Handout and then answer the following questions about the procedures.
More informationFebruary 6. Physics 272. Spring 2014 Prof. Philip von Doetinchem
Physics 272 February 6 Spring 2014 http://www.phys.hawaii.edu/~philipvd/pvd_14_spring_272_uhm.html Prof. Philip von Doetinchem philipvd@hawaii.edu Phys272  Spring 14  von Doetinchem  216 Summary Charges
More informationObjectives. Capacitors 262 CHAPTER 5 ENERGY
Objectives Describe a capacitor. Explain how a capacitor stores energy. Define capacitance. Calculate the electrical energy stored in a capacitor. Describe an inductor. Explain how an inductor stores energy.
More informationChapter 7: Polarization
Chapter 7: Polarization Joaquín Bernal Méndez Group 4 1 Index Introduction Polarization Vector The Electric Displacement Vector Constitutive Laws: Linear Dielectrics Energy in Dielectric Systems Forces
More informationPhysics 1653 Exam 3  Review Questions
Physics 1653 Exam 3  Review Questions 3.0 Two uncharged conducting spheres, A and B, are suspended from insulating threads so that they touch each other. While a negatively charged rod is held near, but
More informationLab 4  Capacitors & RC Circuits
Lab 4 Capacitors & RC Circuits L41 Name Date Partners Lab 4 Capacitors & RC Circuits OBJECTIVES To define capacitance and to learn to measure it with a digital multimeter. To explore how the capacitance
More informationCoefficient of Potential and Capacitance
Coefficient of Potential and Capacitance Lecture 12: Electromagnetic Theory Professor D. K. Ghosh, Physics Department, I.I.T., Bombay We know that inside a conductor there is no electric field and that
More informationELECTROSTATICS. Ans: It is a fundamental property of matter which is responsible for all electrical effects
ELECTROSTATICS One Marks Questions with Answers: 1.What is an electric charge? Ans: It is a fundamental property of matter which is responsible for all electrical effects 2. Write the SI unit of charge?
More informationEDEXCEL NATIONAL CERTIFICATE/DIPLOMA UNIT 5  ELECTRICAL AND ELECTRONIC PRINCIPLES NQF LEVEL 3 OUTCOME 2  CAPACITANCE
EDEXCEL NATIONAL CERTIFICATE/DIPLOMA UNIT 5  ELECTRICAL AND ELECTRONIC PRINCIPLES NQF LEVEL 3 OUTCOME 2  CAPACITANCE 2 Understand the concepts of capacitance and determine capacitance values in DC circuits
More information( )( 10!12 ( 0.01) 2 2 = 624 ( ) Exam 1 Solutions. Phy 2049 Fall 2011
Phy 49 Fall 11 Solutions 1. Three charges form an equilateral triangle of side length d = 1 cm. The top charge is q =  4 μc, while the bottom two are q1 = q = +1 μc. What is the magnitude of the net force
More informationLAB 4: CAPACITORS AND RC CIRCUITS
1 Name Date Partner(s) OBJECTIVES LAB 4: CAPACITORS AND RC CIRCUITS! To define capacitance and to learn to measure it with a digital multimeter.! To discover how the capacitance of conducting parallel
More informationMeasurement of Capacitance
Measurement of Capacitance PreLab Questions Page Name: Class: Roster Number: Instructor:. A capacitor is used to store. 2. What is the SI unit for capacitance? 3. A capacitor basically consists of two
More informationCAPACITIVE REACTANCE. We have already discussed the operation of a capacitor in a DC circuit, however let's just go over the main principles again.
Reading 13 Ron Bertrand VK2DQ http://www.radioelectronicschool.com CAPACITOR IN A DC CIRCUIT CAPACITIVE REACTANCE We have already discussed the operation of a capacitor in a DC circuit, however let's just
More informationObjectives for the standardized exam
III. ELECTRICITY AND MAGNETISM A. Electrostatics 1. Charge and Coulomb s Law a) Students should understand the concept of electric charge, so they can: (1) Describe the types of charge and the attraction
More informationRVRUSA LCC. Capacitance & Capacitors (Bogart, page 285)
Capacitance & Capacitors (Bogart, page 285) Capacitance is a measure of a component s ability to store charge. A capacitor is a device specially designed to have a certain amount of capacitance. This ability
More informationProblem Solving 4: Capacitance, Stored Energy, Capacitors in Parallel and Series, Dielectrics
Problem Solving 4: Capacitance, Stored Energy, Capacitors in Parallel and Series, Dielectrics Section Table Names Hand in one copy per group at the end of the Friday Problem Solving Session. OBJECTIVES
More informationKirchhoff's Rules and Applying Them
[ Assignment View ] [ Eðlisfræði 2, vor 2007 26. DC Circuits Assignment is due at 2:00am on Wednesday, February 21, 2007 Credit for problems submitted late will decrease to 0% after the deadline has passed.
More informationPeople s Physics Book
The Big Idea When current flows through wires and resistors in a circuit as a result of an electric potential, charge does not build up significantly anywhere on the path. Capacitors are devices placed
More informationResistorCapacitor (RC) Circuits
ResistorCapacitor (RC) Circuits Introduction In this second exercise dealing with electrical circuitry, you will work mainly with capacitors, which are devices that are used to store charge for later
More informationEpisode 126: Capacitance and the equation C =Q/V
Episode 126: Capacitance and the equation C =Q/V Having established that there is charge on each capacitor plate, the next stage is to establish the relationship between charge and potential difference
More informationStudent Content Brief Advanced Level
Student Content Brief Advanced Level Electric Circuits Background Information There are a variety of forces acting on the body of the Sea Perch. One important force is pushing electrons through the wires
More informationElectrostatics Problems
Name AP Physics B Electrostatics Problems Date Mrs. Kelly 1. How many excess electrons are contained in a charge of 30 C? 2. Calculate and compare the gravitational and electrostatic force between an electron
More informationThe current that flows is determined by the potential difference across the conductor and the resistance of the conductor (Ohm s law): V = IR P = VI
PHYS1000 DC electric circuits 1 Electric circuits Electric current Charge can move freely in a conductor if an electric field is present; the moving charge is an electric current (SI unit is the ampere
More informationLooking at Capacitors
Module 2 AC Theory Looking at What you'll learn in Module 2: In section 2.1 Common capacitor types and their uses. Basic Circuit Symbols for. In section 2.2 Charge & Discharge How capacitors work. What
More informationElectrical Energy, Potential and Capacitance. AP Physics B
Electrical Energy, Potential and Capacitance AP Physics B Electric Fields and WORK In order to bring two like charges near each other work must be done. In order to separate two opposite charges, work
More informationMULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.
MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 1) If the voltage at a point in space is zero, then the electric field must be A) zero. B) positive.
More informationRC Circuits. Honors Physics Note 002 c Alex R. Dzierba Honors Physics P222  Spring, 2004
R ircuits Honors Physics Note 2 c Alex R. Dziera Honors Physics P222  Spring, 24 Introduction This note concerns the ehavior of circuits that include cominations of resistors, capacitors and possily a
More informationChapter 18. Electric Forces and Electric Fields
My lecture slides may be found on my website at http://www.physics.ohiostate.edu/~humanic/  Chapter 18 Electric Forces and Electric Fields
More informationWhen we do not get specific resistor values we have to either use variable resistors such as
RESISTOR COMBINATIONS When we do not get specific resistor values we have to either use variable resistors such as potentiometers or presets to obtain such precise values. Pots are too expensive to use
More informationExperiment 9 ~ RC Circuits
Experiment 9 ~ RC Circuits Objective: This experiment will introduce you to the properties of circuits that contain both resistors AND capacitors. Equipment: 18 volt power supply, two capacitors (8 µf
More informationCh. 20 Electric Circuits
Ch. 0 Electric Circuits 0. Electromotive Force Every electronic device depends on circuits. Electrical energy is transferred from a power source, such as a battery, to a device, say a light bulb. Conducting
More informationExam 2 Practice Problems Part 1 Solutions
MASSACHUSETTS INSTITUTE OF TECHNOLOGY Department of Physics Exam Practice Problems Part 1 Solutions Problem 1 Electric Field and Charge Distributions from Electric Potential An electric potential V ( z
More informationStoring And Releasing Charge In A Circuit
Storing And Releasing Charge In A Circuit Topic The characteristics of capacitors Introduction A capacitor is a device that can retain and release an electric charge, and is used in many circuits. There
More informationLast Name: First Name: Physics 102 Spring 2006: Exam #2 MultipleChoice Questions 1. A charged particle, q, is moving with speed v perpendicular to a uniform magnetic field. A second identical charged
More informationEE301 Lesson 14 Reading: 10.110.4, 10.1110.12, 11.111.4 and 11.1111.13
CAPACITORS AND INDUCTORS Learning Objectives EE301 Lesson 14 a. Define capacitance and state its symbol and unit of measurement. b. Predict the capacitance of a parallel plate capacitor. c. Analyze how
More informationCapacitors. We charge a capacitor by connecting the two plates to a potential difference, such as a battery:
RC Circuits PHYS 1112L Capacitors A capacitor is an electrical component that stores charge. The simplest capacitor is just two charged metal plates separated by a nonconducting material: In the diagram
More informationCapacitance. IV. Capacitance. 1a. Leyden Jar. Battery of Leyden Jars. A. The Electric Condenser. B. Dielectrics. C. Energy in Electric Field
IV. apacitance apacitance A. The Electric ondenser B. Dielectrics Revised: Feb5. Energy in Electric Field Sections.79 and 3.8 in book A. The Electric ondenser 3. History of the apacitor 4 ) History of
More informationFall 97 Test 1, P. 2
2102 Fall 97 Test 1 Fall 97 Test 1, P. 2 Fall 97 Test 1, P. 3 Fall 97 Test 1, P. 4 Fall 97 Test 1, P. 5 5. (10 points) A spherical rubber balloon has a charge uniformly distributed over is surface. The
More informationELECTRIC FIELD LINES AND EQUIPOTENTIAL SURFACES
ELECTRIC FIELD LINES AND EQUIPOTENTIAL SURFACES The purpose of this lab session is to experimentally investigate the relation between electric field lines of force and equipotential surfaces in two dimensions.
More informationChapter 18 Electric Forces and Electric Fields. Key Concepts:
Chapter 18 Lectures Monday, January 25, 2010 7:33 AM Chapter 18 Electric Forces and Electric Fields Key Concepts: electric charge principle of conservation of charge charge polarization, both permanent
More informationJanuary 30. Physics 272. Spring Prof. Philip von Doetinchem
Physics 272 January 30 Spring 2014 http://www.phys.hawaii.edu/~philipvd/pvd_14_spring_272_uhm.html Prof. Philip von Doetinchem philipvd@hawaii.edu Phys272  Spring 14  von Doetinchem  140 Summary General
More informationChapter 21 Electric Current and DirectCurrent Circuit
Chapter 2 Electric Current and DirectCurrent Circuit Outline 2 Electric Current 22 Resistance and Ohm s Law 23 Energy and Power in Electric Circuit 24 Resistance in Series and Parallel 25 Kirchhoff
More informationUNIT 24: CAPACITORS AND RC CIRCUITS Approximate Time Two 100minute Sessions
Name St.No.  Date(YY/MM/DD) / / Section Group # UNIT 24: CAPACITORS AND RC CIRCUITS Approximate Time Two 100minute Sessions + + + +     The most universal and significant concept to come out of the
More informationWhat will we learn in this chapter?
Chapter 19: Current, resistance, circuits What will we learn in this chapter? What are currents? Resistance and Ohm s law (no, there are no 3 laws). Circuits and electric power. Resistors in series and
More informationElectrical discharge in air e.g. lightning
Static Electricity electron transfer causes static electricity results from an imbalance of charges can occur by induction, friction, and contact You need to describe the direction of motion of charges
More informationChapter 18. Direct Current Circuits
Chapter 18 Direct Current Circuits Sources of emf The source that maintains the current in a closed circuit is called a source of emf Any devices that increase the potential energy of charges circulating
More informationChapter 7. DC Circuits
Chapter 7 DC Circuits 7.1 Introduction... 73 Example 7.1.1: Junctions, branches and loops... 74 7.2 Electromotive Force... 75 7.3 Electrical Energy and Power... 79 7.4 Resistors in Series and in Parallel...
More informationHow many laws are named after Kirchhoff?
Chapter 32. Fundamentals of Circuits Surprising as it may seem, the power of a computer is achieved simply by the controlled flow of charges through tiny wires and circuit elements. Chapter Goal: To understand
More informationEnergy in Electrical Systems. Overview
Energy in Electrical Systems Overview How can Potential Energy be stored in electrical systems? Battery Stored as chemical energy then transformed to electrical energy on usage Water behind a dam Water
More informationChapter 25 : Electric circuits
Chapter 25 : Electric circuits Voltage and current Series and parallel circuits Resistors and capacitors Kirchoff s rules for analysing circuits Electric circuits Closed loop of electrical components around
More information4/16/ Bertrand
Physics B AP Review: Electricity and Magnetism Name: Charge (Q or q, unit: Coulomb) Comes in + and The proton has a charge of e. The electron has a charge of e. e = 1.602 1019 Coulombs. Charge distribution
More informationElectric Circuits. Concepts and Principles. Electric Circuits as Applied Physics. The Resistor
. Electric ircuits oncepts and Principles Electric ircuits as Applied Physics Electric circuits are one of the most practical applications of our understanding of electric and magnetic fields. In general,
More informationQ24.1 The two conductors a and b are insulated from each other, forming a capacitor. You increase the charge on a to +2Q and increase the charge on b
Q24.1 The two conductors a and b are insulated from each other, forming a capacitor. You increase the charge on a to +2Q and increase the charge on b to 2Q, while keeping the conductors in the same positions.
More informationElectricity & Optics
Physics 24100 Electricity & Optics Lecture 9 Chapter 24 sec. 35 Fall 2012 Semester Matthew Jones Thursday s Clicker Question To double the capacitance of a parallel plate capacitor, you should: (a) Double
More informationCapacitors Lab. In order to investigate electric fields you will need the following equipment. Homemade parallel capacitor with wax paper in between
Capacitors Lab 1 Equipment In order to investigate electric fields you will need the following equipment Homemade parallel capacitor with wax paper in between DC voltage supply Electrometer Variable capacitor
More informationCh 18 Direct Current Circuits. concept #2, 5, 10, 12, 13, 23 Problems #1, 5, 6, 11, 17, 25, 31, 32, 33, 35, 36, 37
Ch 18 Direct Current Circuits concept #2, 5, 10, 12, 13, 23 Problems #1, 5, 6, 11, 17, 25, 31, 32, 33, 35, 36, 37 currents are maintained by a source of emf (battery, generator) Sources of emf act as charge
More informationElectric Field Mapping Lab 3. Precautions
HB 092507 Electric Field Mapping Lab 3 1 Electric Field Mapping Lab 3 Equipment mapping board, Uprobe, resistive boards, templates, dc voltmeter (431B), 4 long leads, 16 V dc for wall strip Reading
More informationProfs. A. Petkova, A. Rinzler, S. Hershfield. Exam 2 Solution
PHY2049 Fall 2009 Profs. A. Petkova, A. Rinzler, S. Hershfield Exam 2 Solution 1. Three capacitor networks labeled A, B & C are shown in the figure with the individual capacitor values labeled (all units
More informationHomework 6 Solutions PHYS 212 Dr. Amir
Homework 6 Solutions PHYS Dr. Amir Chapter 5: 9. (II) A 00W lightbulb has a resistance of about Ω when cold (0 C) and 0 Ω when on (hot). Estimate the temperature of the filament when hot assuming an average
More informationLab 5 RC Circuits: Charge Changing in Time Observing the way capacitors in RC circuits charge and discharge.
Print Your Name Lab 5 RC Circuits: Charge Changing in Time Observing the way capacitors in RC circuits charge and discharge. Print Your Partners' Names Instructions October 15, 2015October 13, 2015 Read
More informationTwo kinds of electrical charges
ELECTRICITY NOTES Two kinds of electrical charges Positive charge Negative charge Electrons are negatively charged Protons are positively charged The forces from positive charges are canceled by forces
More informationPhysics 9e/Cutnell. correlated to the. College Board AP Physics 1 Course Objectives
Physics 9e/Cutnell correlated to the College Board AP Physics 1 Course Objectives Big Idea 1: Objects and systems have properties such as mass and charge. Systems may have internal structure. Enduring
More informationCHAPTER 19: DC Circuits. Answers to Questions
HAPT 9: D ircuits Answers to Questions. The birds are safe because they are not grounded. Both of their legs are essentially at the same voltage (the only difference being due to the small resistance of
More informationHW7 Solutions Notice numbers may change randomly in your assignments and you may have to recalculate solutions for your specific case.
HW7 Solutions Notice numbers may change randomly in your assignments and you may have to recalculate solutions for your specific case. Tipler 24.P.021 (a) Find the energy stored in a 20.00 nf capacitor
More informationCHAPTER 14  CAPACITORS QUESTION & PROBLEM SOLUTIONS
Solutionsh 14 (apacitors) HAPTER 14  APAITORS QUESTION & PROBLEM SOLUTIONS 141) You have a power supply whose low voltage plate A plate B "ground" terminal is attached to a resistor whose R resistance
More informationOCR (A) specifications: 5.4.7a,b,c,d,e,f,g,h. Chapter 7 Capacitors
OCR (A) specifications: 5.4.7a,b,c,d,e,f,g,h Chapter 7 Capacitors Worksheet Worked examples Practical : Determining the capacitance of a parallelplate capacitor Practical 2: Determining the capacitance
More informationPhysics 9 Fall 2009 Homework 6  Solutions
. Chapter 32  Exercise 8. Physics 9 Fall 29 Homework 6  s How much power is dissipated by each resistor in the figure? First, let s figure out the current in the circuit. Since the two resistors are
More informationElectric Currents. Electric Potential Energy 11/23/16. Topic 5.1 Electric potential difference, current and resistance
Electric Currents Topic 5.1 Electric potential difference, current and resistance Electric Potential Energy l If you want to move a charge closer to a charged sphere you have to push against the repulsive
More informationLecture Presentation Chapter 23 Circuits
Lecture Presentation Chapter 23 Circuits Suggested Videos for Chapter 23 Prelecture Videos Analyzing Circuits Series and Parallel Circuits Capacitor Circuits Video Tutor Solutions Circuits Class Videos
More informationPhys 102 Spg Exam No. 2 Solutions
Phys 102 Spg. 2008 Exam No. 2 Solutions I. (20 pts) A 10turn wire loop measuring 8.0 cm by 16.0 cm carrying a current of 2.0 A lies in the horizontal plane and is free to rotate about a horizontal axis
More informationChapter 4. Electrostatic Fields in Matter
Chapter 4. Electrostatic Fields in Matter 4.1. Polarization A neutral atom, placed in an external electric field, will experience no net force. However, even though the atom as a whole is neutral, the
More informationChapter 22: Electric Flux and Gauss s Law
22.1 ntroduction We have seen in chapter 21 that determining the electric field of a continuous charge distribution can become very complicated for some charge distributions. t would be desirable if we
More informationGravitational Fields: Review
Electric Fields Review of gravitational fields Electric field vector Electric fields for various charge configurations Field strengths for point charges and uniform fields Work done by fields & change
More informationElectromagnetism  Lecture 5. Capacitors & Electrostatic Energy
Electromagnetism  Lecture 5 Capacitors & Electrostatic Energy Examples of Capacitors Calculations of Capacitance Electrostatic Energy Introduction of Dielectrics General Result for Electrostatic Energy
More informationPHYS2212 LAB Coulomb s Law and the Force between Charged Plates
PHYS2212 LAB Coulomb s Law and the Force between Charged Plates Objectives To investigate the electrostatic force between charged metal plates and determine the electric permittivity of free space, ε
More informationAP Physics Capacitance & Dielectrics; Current & Resistance; D.C. Circuits
A hysics Capacitance & Dielectrics; Current & esistance; D.C. Circuits art I. Multiple Choice (4 points each) Choose the one best answer to each of the following problems. 1 (A). A parallelplate capacitor
More informationExercises on Voltage, Capacitance and Circuits. A d = (8.85 10 12 ) π(0.05)2 = 6.95 10 11 F
Exercises on Voltage, Capacitance and Circuits Exercise 1.1 Instead of buying a capacitor, you decide to make one. Your capacitor consists of two circular metal plates, each with a radius of 5 cm. The
More informationEðlisfræði 2, vor 2007
[ Assignment View ] [ Pri Eðlisfræði 2, vor 2007 31. Alternating Current Circuits Assignment is due at 2:00am on Wednesday, March 21, 2007 Credit for problems submitted late will decrease to 0% after the
More informationChapter 17: Electric Potential
hapter 17: Electric Potential Electric Potential Energy Electric Potential How are the Efield and Electric Potential related? Motion of Point harges in an Efield apacitors Dielectrics 1 Electric Potential
More informationPart 1. Part 1. Electric Current. and Direct Current Circuits. Electric Current. Electric Current. Chapter 19. Electric Current
Electric Current Electric Current and Direct Current Circuits Chapter 9 Resistance and Ohm s Law Power in Electric Circuits Direct Current Circuits Combination Circuits Real life is mostly dynamic Part
More informationBASIC ELECTRONICS PROF. T.S. NATARAJAN DEPT OF PHYSICS IIT MADRAS LECTURE4 SOME USEFUL LAWS IN BASIC ELECTRONICS
BASIC ELECTRONICS PROF. T.S. NATARAJAN DEPT OF PHYSICS IIT MADRAS LECTURE4 SOME USEFUL LAWS IN BASIC ELECTRONICS Hello everybody! In a series of lecture on basic electronics, learning by doing, we now
More informationLevel 2 Physics: Demonstrate understanding of electricity and electromagnetism
Level 2 Physics: Demonstrate understanding of electricity and electromagnetism Static Electricity: Uniform electric field, electric field strength, force on a charge in an electric field, electric potential
More information1: (ta initials) 2: first name (print) last name (print) brock id (ab13cd) (lab date)
1: (ta initials) 2: first name (print) last name (print) brock id (ab13cd) (lab date) Experiment 1 Capacitance In this Experiment you will learn the relationship between the voltage and charge stored on
More informationHW6 Solutions Notice numbers may change randomly in your assignments and you may have to recalculate solutions for your specific case.
HW6 Solutions Notice numbers may change randomly in your assignments and you may have to recalculate solutions for your specific case. Tipler 22.P.053 The figure below shows a portion of an infinitely
More informationChapter 28. Direct Current Circuits
Chapter 28 Direct Current Circuits Direct Current When the current in a circuit has a constant direction, the current is called direct current Most of the circuits analyzed will be assumed to be in steady
More informationUniversity Physics 227N/232N Current and Ohm s Law, Resistors, Circuits, and Kirchoff Lab this Friday, Feb 28 So NO QUIZ this Friday!
University Physics 227N/232N Current and Ohm s Law, Resistors, Circuits, and Kirchoff Lab this Friday, Feb 28 So NO QUIZ this Friday! Dr. Todd Satogata (ODU/Jefferson Lab) and Fred Miller satogata@jlab.org
More informationElectromagnetism Laws and Equations
Electromagnetism Laws and Equations Andrew McHutchon Michaelmas 203 Contents Electrostatics. Electric E and Dfields............................................. Electrostatic Force............................................2
More informationCharge and Discharge of a Capacitor
Charge and Discharge of a Capacitor INTRODUCTION Capacitors 1 are devices that can store electric charge and energy. Capacitors have several uses, such as filters in DC power supplies and as energy storage
More information2 A Dielectric Sphere in a Uniform Electric Field
Dielectric Problems and Electric Susceptability Lecture 10 1 A Dielectric Filled Parallel Plate Capacitor Suppose an infinite, parallel plate capacitor with a dielectric of dielectric constant ǫ is inserted
More information